U.S. patent number 7,305,905 [Application Number 10/754,284] was granted by the patent office on 2007-12-11 for rotatable member with an annular groove for dynamic balancing during rotation.
This patent grant is currently assigned to The Bergquist Torrington Company. Invention is credited to Russel H. Marvin, John F. O'Connor, Jr., Drew M. Rocky.
United States Patent |
7,305,905 |
Rocky , et al. |
December 11, 2007 |
Rotatable member with an annular groove for dynamic balancing
during rotation
Abstract
A rotatable member is adapted for dynamic balancing by the
addition of balancing weights in the form of high speed projectiles
fired at the member during rotation in timed relationship with the
rotation of the member so as to impact the member at specific
circumaxial locations required for balancing the member. The member
has an annular groove for receiving the projectiles and securing
the same at the desired locations. The groove has a cross sectional
configuration slightly smaller than that of the projectile in at
least one direction of measurement so as to engage and capture the
projectile in retention in the groove.
Inventors: |
Rocky; Drew M. (Woodbury,
CT), Marvin; Russel H. (Goshen, CT), O'Connor, Jr.; John
F. (New Hartford, CT) |
Assignee: |
The Bergquist Torrington
Company (Torrington, CT)
|
Family
ID: |
34739353 |
Appl.
No.: |
10/754,284 |
Filed: |
January 9, 2004 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050150322 A1 |
Jul 14, 2005 |
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Current U.S.
Class: |
74/570.2;
416/144; 416/190; 74/572.2; 74/572.4 |
Current CPC
Class: |
F16F
15/32 (20130101); Y10T 74/2109 (20150115); Y10T
74/2121 (20150115); Y10T 74/2111 (20150115) |
Current International
Class: |
F16F
15/22 (20060101); B63H 1/00 (20060101); B63H
3/00 (20060101); B64C 11/00 (20060101) |
Field of
Search: |
;74/572.4,570.1-570.3,570.21,570.11,573.1,572.2
;416/144,190,178,187 ;409/141 ;415/189 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Luong; Vinh T.
Attorney, Agent or Firm: Haugen Law Firm PLLP
Claims
The invention claimed is:
1. A rotatable member adapted for dynamic balancing by the addition
of balancing weights in the form of projectiles fired at the member
during rotation in timed relationship with the rotation of the
member so as to impact the member at specific circumaxial locations
for balancing of the member, said member taking the form of a
centrifugal air impeller having a backplate residing in a radial
plane, a circumaxially spaced series of longitudinal air moving
blades extending axially therefrom and a radial end ring supporting
blade end portions opposite the backplate, one of the backplate and
end ring having an annular groove for receiving projectiles and
securing the same at the desired locations for balancing the ring,
a wall of the groove having a cross-sectional configuration
approximating that of the projectile but slightly smaller than that
of the projectile at least after impact in at least one direction
of measurement so as to engage and capture the projectile for
retention in the groove.
2. A rotatable member as set forth in claim 1 wherein the annular
groove is provided in the end ring.
3. A rotatable member as set forth in claim 1 wherein the groove is
configured and dimensioned to retain the projectile
frictionally.
4. A rotatable member as set forth in claim 1 wherein the groove is
configured and dimensioned to retain the projectile by positive
engagement therewith.
5. A rotatable member as set forth in claim 1 wherein the groove
has a mouth portion which is narrower than an interior portion of
the groove with a first mouth defining wall portion thereof being
sufficiently flexible to enable entry of the projectile to the
interior portion of the groove.
6. A rotatable member as set forth in claim 5, including a second
mouth defining wall portion that is rigid.
7. A rotatable member as set forth in claim 6 wherein said second
mouth defining wall portion is inclined from the line of flight of
the projectile in the range of 10-55 degrees whereby to assist in
directing projectiles into the groove.
8. A rotatable member as set forth in claim 7 wherein the angle of
inclination of the second mouth defining wall portion is about 30
degrees.
9. A rotatable member as set forth in claim 6 wherein the groove is
so configured and dimensioned that the first mouth defining wall
portion engages the projectile after entry and exerts a clamping
force to positively retain the projectile in the groove.
10. A rotatable member as set forth in claim 1 wherein a series of
small transverse ribs are provided in the groove and are spaced
circumaxially so as to engage projectile in the groove and secure
the same against accidental or inadvertent movement circumaxially
along the groove.
11. A rotatable member as set forth in claim 10 wherein the ribs
are of a material softer than that of the projectile so as to be at
least partially crushed by the latter.
12. A rotatable member as set forth in claim 1 wherein the
projectile is spherical and the groove is at least partially
cylindrical.
13. A rotatable member as set forth in claim 1 wherein the member
is of molded thermoplastic construction and the projectile is of
metallic construction.
14. A rotatable member as set forth in claim 1 wherein both the
member and the projectile are of metallic construction.
Description
BACKGROUND OF THE INVENTION
Manual dynamic balancing of rotatable members is still a common
practice with the member being rotated to determine the points of
unbalance, the rotation stopped to attach weights manually, and the
member perhaps rotated a second time to check the balance.
Obviously, this is a tedious and time-consuming procedure. Attempts
at automation have not been widely successful.
U.S. Pat. No. 2,432,659 to Criswell first determines the locations
requiring added weight and then sprays "small particles of metal"
repeatedly until the member is balanced.
U.S. Pat. No. 2,937,613 discloses firing a "Body" at a groove in a
rotating member but does not disclose any means for capturing and
retaining the "Body".
U.S. Pat. No. 3,968,769 to Gusarov et al projects glue onto the
circumaxial locations requiring balancing.
U.S. Pat. No. 5,992,232 to Saitoh ejects a liquid balancing agent,
which requires curing.
Provisional Patent Application entitled Method and Apparatus for
Balancing Fan and Blower Assemblies, filed of even date herewith,
discloses a system similar to the foregoing patents but which fires
projectiles of metal or the like at a rotating member for balancing
the same. The system is highly efficient but requires a means of
capturing the projectiles and positively retaining the same at the
desired circumaxial locations.
The foregoing patents as well as the Provisional Application are
hereby incorporated herein by reference.
It is the general object of the present invention to provide
projectile capturing and retaining means on a rotating member in a
simple and efficient manner.
SUMMARY OF THE INVENTION
In fulfillment of the foregoing object and in accordance with the
present invention, an annular groove is provided in a member to be
balanced and has a cross sectional configuration slightly smaller
than that of the projectile at least after impact in at least one
direction of measurement so as to engage and capture the projectile
for retention in the groove. The groove may retain the projectile
frictionally or, preferably, the projectile may be retained by
positive engagement of the groove wall therewith. This condition
may result from a groove design wherein the mouth of the groove is
narrower than the interior with at least one mouth-defining portion
of the groove wall being flexible for entry of the projectile to
the interior of the groove. Preferably, the side of the mouth
opposite the flexible portion is inclined from the line of flight
of the projectile in the range of 10 to 55 degrees whereby to
direct errant projectiles into the groove, and more specifically
approximately 30 degrees. Once the projectile has entered the
groove, the flexible portion of the groove wall engages and
positively clamps the same therein. Alternatively, positive
retention of a projectile in a groove may be provided for with a
relatively soft projectile, which expands on impact within a groove
so as to become larger than the mouth of the groove.
Once captured in a groove it is of course important that unintended
or accidental circumaxial movement of the projectiles along the
groove be positively prevented. To meet this need, small transverse
ribs are provided in a spaced circumaxial series and one or more
ribs may be partially deformed on impact whereby to provide the
necessary retention of the projectiles at the specific locations
required for balancing the rotatable member.
Examples of rotatable members which can be advantageously balanced
with the aid of a balancing groove of the invention are air
impellers and small electric motors. Centrifugal air impellers and
small permanent magnet D.C. motors are specifically discussed
herein below.
Finally, a method of balancing employing projectiles fired at
rotating members is also discussed below.
DESCRIPTION OF THE DRAWINGS
FIG. 1 of the drawings illustrates a centrifugal air impeller
partially in section provided with a pair of balancing grooves in
accordance with the invention.
FIG. 2 is an enlarged fragmentary top view partially in section of
a balancing groove.
FIG. 3 is an enlarged cross sectional view of a balancing groove
with a projectile in flight and about to enter the groove.
FIG. 4 is an enlarged fragmentary longitudinal section of a groove
showing a plurality of transverse ribs engaging and retaining a
projectile against movement along the groove.
FIG. 5 is an enlarged fragmentary cross sectional view of a groove
and projectile of an alternative embodiment of the invention.
FIG. 6 is a view of still another embodiment of the invention.
FIG. 7 is a view in partial cross section of a small electric motor
provided with a pair of balancing grooves.
FIG. 8 is a fragmentary perspective view of a centrifugal air
impeller having a specific blade, end ring and back plate
construction and which is provided with a balancing grooves in its
end ring and backplate.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring particularly to FIG. 1, it will be observed that a
centrifugal air impeller indicated generally at 10 is provided with
a pair of annular balancing grooves 12 and 14 respectively in end
ring 16 and back plate 18. Parallel circumaxially spaced
longitudinally extending air moving blades 20, 20 interconnect the
end ring 16 and the back plate 18. The grooves 12 and 14 may be
identical in construction and are best illustrated in FIGS. 2 and
3.
Referring particularly to FIG. 3, it will be observed that the
mouth of the groove 14 at A is somewhat narrower than the interior.
A left hand wall portion or lip 22 would tend to block entry of a
projectile larger than A but is flexible so as to bend leftwardly
sufficiently to allow the projectile to pass and assume the broken
line position in the interior of the groove as shown. In the broken
line position the projectile is engaged by the lip as it returns to
its normal position and a clamping force is exerted by the lip on
the projectile urging it against the opposite wall of the groove.
Thus, the projectile is captured and positively retained in the
groove.
Still referring to FIG. 3, the wall portion 21 of the groove
opposite the lip 22 is shown inclined toward the interior of the
groove at an angle ".alpha." with the line of flight of the
projectile, the purpose of this inclined portion is to direct
errant projectiles into the groove and the angle of inclination
from the projectile line of flight should fall in the range of
10-55 degrees. Preferably the angle should be approximately 30
degrees. It should also be noted that the lip 22 has a shallow
arcuate surface 26 facing inwardly so as to be engaged by
projectiles causing the lip to Flex-Ability Concepts outwardly and
opening the mouth for projectile entry.
Further in accordance with the present invention,
.sup.3anti-rotation.sup.2 ribs 28,28 are provided to retain
projectiles in the groove against accidental or inadvertent
movement along the groove. As best illustrated in FIGS. 3 and 4, a
plurality of ribs 28, 28 are provided in circumaxially spaced
relationship along the base of each groove. A projectile such as 24
in FIG. 4 may partially crush a single rib as shown or it may rest
between two ribs perhaps partially crushing each. In either event
the projectile is restrained against movement along the groove.
In the embodiment of the invention thus far described, the air
impeller and thus the balancing groove are of molded plastic
construction and the projectile is of metallic construction, the
latter actually taking the form of a conventional BB of the type
fired from a child's toy rifle. Alternatively, both elements may be
of metallic construction or, as will be seen, a relatively soft
material may be employed for the projectile and a somewhat harder
material for the groove wall.
FIG. 5 illustrates an alternative embodiment of the invention
wherein a relatively soft material such as plastic or lead is used
for the projectile 24a and a somewhat harder material such as steel
is used for the groove walls 30. The projectile in this instance
should be slightly smaller than the mouth A of the groove 14a.
Thus, the projectile freely enters the groove and on impact with
the rear wall of the groove deforms slightly so as to flatten
somewhat and engage the side walls of the groove which are inclined
to make the rear of the groove wider than its mouth. As will be
apparent, the projectile is thus captured and positively held in
the groove at the desired location. A series of small ribs 32,32
may be provided as above to retain the projectile in position
circumaxially.
A further alternative embodiment of the invention is shown in FIG.
6. A groove 14b has walls 34,34 which incline inwardly from the
mouth of the groove to engage a projectile with progressively
greater force as it proceeds into the groove. This of course
results in a substantial frictional retaining force against
withdrawal of the projectile from the groove. To enhance this
retaining force small longitudinally extending ribs 36, 36 may be
provided on the sidewalls 34, 34. The ribs may be slightly deformed
by the projectile to provide a hybrid frictional and positive
retention of the projectile.
A further application of balancing grooves is illustrated in FIG.
7. Small electric motor 40 which may be of the permanent magnet DC
type, has an external rotor 42 and a stator 44. Depending on the
axial dimension of the rotor, one or two balancing grooves may be
required. As shown, two grooves 46,48 are provided at opposite
sides of the rotor and face in opposite directions. The grooves 46,
48 may be identical and they may also be identical with the
above-described grooves 12 and 14 on the air impeller of FIG.
1.
FIG. 8 illustrates the application of balancing grooves to a
specific design of a centrifugal air impeller fully disclosed in
U.S. patent application entitled IMPROVED INJECTION MOLDED
CENTRIFUGAL AIR IMPELLER filed Oct. 31, 2003, hereby incorporated
herein by reference. The impeller design emphasizes the provision
of a mold parting line at an intermediate longitudinal portion of
blades 45,45 as shown by the broken Line 46. Balancing grooves 49,
50 are provided respectively at end ring 52 and back plate 54 and
may be identical with the grooves of FIG. 1. The end ring 52 is
considerably enlarged relative to the end ring of the
aforementioned patent application to accommodate the balancing
groove 49.
Finally, the general method of balancing a rotating member as set
forth in the aforementioned patent applications and the Provisional
application incorporated herein by reference is greatly enhanced by
the addition of a balancing groove. Thus, an improved method in
accordance balancing, determining a location where a balancing
weight is needed, firing a projectile in timed relationship with
the rotation of the member so that the projectile enters the groove
at the predetermined location, and repeating the foregoing steps as
required to cure additional points of imbalance.
* * * * *